TORONTO - Environment Canada says a brief tornado hit the Shelburne, Ont., area on Thursday evening.

Investigators say the tornado touched down approximately six kilometres northwest of Shelburne and cut a path of damage 500 metres long and 75 metres wide.

The tornado -- rated at "one" on the enhanced Fujita scale -- ripped the roof and two walls off a barn and some pieces were found firmly embedded in the ground 50 to 100 metres away.

Environment Canada says it's the first tornado of the season, not only in Ontario but in all of Canada.

And the town of Huntsville -- already the scene of some flooding and washouts -- is warning residents to prepare for increasing water levels throughout the town.

In the Town of East Gwillimbury, meanwhile, police say about 20 hydro poles were knocked down on Woodbine Avenue between Green Lane and Garfield Wright Boulevard.